Porous Carbon Oxide Nanocomposite Electrodes for High Energy Density Supercapacitors

Abstract

A high energy density supercapacitor is provided by using nanocomposite electrodes having an electrically conductive carbon network having a surface area greater than 2,000 m2 / g and a pseudo-capacitive metal oxide such as MnO2. The conductive carbon network is incorporated into a porous metal oxide structure to introduce sufficient electricity conductivity so that the bulk of metal oxide is utilized for charge storage, and / or the surface of the conductive carbon network is decorated with metal oxide to increase the surface area and amount of pseudo-capacitive metal oxide in the nanocomposite electrode for charge storage.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001]This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 61 / 232,831, filed Aug. 11, 2009 entitled, POROUS GRAPHENE OXIDE NANOCOMPOSITE ELECTRODES FOR HIGH ENERGY DENSITY SUPERCAPACITORS.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to carbon-oxide nanocomposite electrodes for a supercapacitor having both high power density and high energy density.[0004]2. Description of Related Art[0005]During the past two decades, the demand for the storage of electrical energy has increased significantly in the areas of portable, transportation, and load-leveling and central backup applications. The present electrochemical energy storage systems are simply too costly to penetrate major new markets. Still higher performance is required, and environmentally acceptable materials are preferred. Transformational changes in electrical energy storage science and tec...

AI Technical Summary

Benefits of technology

[0025]In this invention, newly designed nanocomposite electrodes allow employment of increasing amount of the pseudo-capacitive oxide by directly supporting the oxide with high surface area graphene carbon and / or coating, so that the graphene carbon is contained within or incorporated into (“decorated”) the pores of a pseudo-capacitive skeleton. Its surface area is further increased by coating the graphene carbon with the same or different pseudo-capacitive oxides. The term “nanocomposite electrode” herein is defined to mean that, at least, one of individual components has a particle size less than 100 nanometers (nm). The electrode porosity ranges from 30 vol. % to 65 vol. % porous. Preferably, two nanocomposite electrodes are disposed on either side of a separator and each electrode contacts an outside current collector. The term “decorated”“decorating” as used herein means coated / contained within or incorporated into.

Problems solved by technology

The present electrochemical energy storage systems are simply too costly to penetrate major new markets.

NiMH batteries were the initial workhorse for electronic devices such as computers and cell phones, but they have almost been completely displaced from that market by lithium-ion batteries because of the latter's higher energy storage capacity.

Today, NiMH technology is the principal battery used in hybrid electric vehicles, but it is likely to be displaced by the higher power energy and now lower cost lithium batteries, if the latter's safety and lifetime can be improved.

One of the major limitations for supercapacitor for its prevalent application is its slower energy density when compared with fuel cell and battery.

Unfortunately, the oxides show low electrical conductivity so that they must be supported by a conductive component such as activated carbon.

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